Determining the absence or presence of fluid in a dialysis system

ABSTRACT

This disclosure relates to detecting fluid in medical tubing. In certain aspects, a method is performed by a data processing apparatus. The method includes controlling repetitive activation of the ultrasonic transmitter. The method also includes receiving a signal from the ultrasonic receiver during an activation of the ultrasonic transmitter. The method also includes determining that fluid is absent or present in a portion of the medical fluid tube based on a comparison between the signal and a threshold value.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation in part of, and claims priority to,U.S. patent application Ser. No. 13/106,431, filed on May 12, 2011,entitled “Medical Tubing Installation Detection,” the entire contents ofwhich are hereby incorporated by reference.

TECHNICAL FIELD

This invention relates to medical tubing installation detection.

BACKGROUND

When kidney failure is diagnosed, patients are typically givenmedication to help control the symptoms and slow the progress of damageto the kidneys. Patients with chronic kidney failure generally takedrugs to control the balance of minerals in the body and prevent areduction of red blood cells (anemia).

Healthy kidneys produce the hormone erythropoietin (often shortened to“EPO”), which stimulates the production of red blood cells in bonemarrow. Red blood cells play a key role in the delivery of oxygen totissues in the body. Insufficient levels of EPO in the body can lead toanemia. This often causes a drop in physical and mental performance andan increased risk for cardio-vascular diseases. To prevent anemia,chronic renal patients frequently receive a synthetic version oferythropoietin (also referred to as “EPO”) that, like the naturalerythropoietin, stimulates the production of red blood cells.

Anemia can be managed using a variety of different drugs. For example,since iron is also needed to produce red blood cells, many dialysispatients also take iron preparations. Venofer® (iron sucrose injection,USP) is indicated in the treatment of iron deficiency anemia in patientsundergoing chronic hemodialysis who are receiving supplemental EPOtherapy.

SUMMARY

In one aspect of the invention, a method is performed by a dataprocessing apparatus. The method includes detecting that a tube isincorrectly installed on a drug delivery device by providing aninstruction for a motor of the drug delivery device to pump a drug andreceiving, after a period of time has passed since providing theinstruction for the motor of the drug delivery device to pump the drug,a signal from a fluid detector connected to the tube, the signalindicating an absence of fluid in the tube.

In another aspect of the invention, a second method is performed by adata processing apparatus. The method includes detecting that a tube isincorrectly installed on a drug delivery device by receiving a firstsignal from a fluid detector connected to the tube, determining a firstmagnitude of the first signal from the fluid detector, and storing thefirst magnitude of the first signal. The method also includes receiving,at a later time, a second signal from the fluid detector connected tothe tube and determining a second magnitude of the second signal fromthe fluid detector. The method also includes comparing the first andsecond magnitudes and determining that the second magnitude is athreshold level greater than the first magnitude.

In another aspect of the invention, a dialysis system includes adialysis machine, a control unit, a medical fluid tube connected to thedialysis machine, and a fluid detector. The dialysis system alsoincludes a computer-readable medium coupled to the control unit havinginstructions stored thereon which, when executed by the one or moreprocessors, cause the one or more processors to perform operations. Theoperations include detecting that a tube is incorrectly installed on adrug delivery device by providing an instruction for a motor of the drugdelivery device to pump a drug and receiving, after a period of time haspassed since providing the instruction for the motor of the drugdelivery device to pump the drug, a signal from a fluid detectorconnected to the tube, the signal indicating an absence of fluid in thetube.

In another aspect of the invention, a dialysis system includes adialysis machine, a control unit, a medical fluid tube connected to thedialysis machine, and a fluid detector. The dialysis system alsoincludes a computer-readable medium coupled to the control unit havinginstructions stored thereon which, when executed by the one or moreprocessors, cause the one or more processors to perform operations. Theoperations include detecting that a tube is incorrectly installed on adrug delivery device by receiving a first signal from a fluid detectorconnected to the tube, determining a first magnitude of the first signalfrom the fluid detector, and storing the first magnitude of the firstsignal. The method also includes receiving, at a later time, a secondsignal from the fluid detector connected to the tube and determining asecond magnitude of the second signal from the fluid detector. Themethod also includes comparing the first and second magnitudes anddetermining that the second magnitude is a threshold level greater thanthe first magnitude.

In another aspect of the invention, a dialysis system includes adialysis machine, a control unit, a medical fluid tube connected to thedialysis machine, an ultrasonic transmitter positioned adjacent to themedical fluid tube, and an ultrasonic receiver positioned adjacent tothe medical fluid tube configured to receive one or more signals inresponse to the activation of the ultrasonic transmitter. The dialysissystem also includes a computer storage medium encoded with computerprogram instructions that when executed by dialysis system, causes thedialysis system to perform operations comprising controlling repetitiveactivation of the ultrasonic transmitter. The operations also includereceiving a signal from the ultrasonic receiver during an activation ofthe ultrasonic transmitter. The operations also include determining thatfluid is absent or present in a portion of the medical fluid tube basedon a comparison between the signal and a threshold value.

Implementations can include one or more of the following features.

In certain implementations, the tube has an external diameter less than0.01 inch.

In certain implementations, the fluid detector is connected to the tubeupstream of the pump.

In certain implementations, the fluid detector is connected between adrug vial and the pump.

In certain implementations, the fluid detector is an ultrasonic fluiddetector.

In some implementations, the drug delivery device includes only oneultrasonic fluid detector connected to the tube.

In certain implementations, the method includes receiving, prior toproviding the instruction for the motor of the drug delivery device topump the drug, a signal from the fluid detector, the signal indicatingan absence of fluid in the tube.

In certain implementations, providing the instruction for the motor topump the drug includes providing the instruction for a duration suchthat the drug is drawn from a drug vial to fill the tube up to the pump.

In some implementations, the signal is received after the duration forwhich the instruction is provided.

In certain implementations, the drug delivery device is a module thatfits into a dialysis machine.

In certain implementations, the method includes providing a visualindication that the tube is incorrectly installed.

In some implementations, the method includes providing an instructionfor a motor of the drug delivery device to pump a drug prior toreceiving the second signal from the fluid detector.

In certain implementations, the first signal is received after a drughas been pumped from the drug vial to fill the tube up to the pump.

In certain implementations, the operations include storing an indicatorof the absence or presence of fluid in a data structure, the datastructure storing a plurality of indicators determined during previousactivations of the ultrasonic transmitter.

In certain implementations, the operations include raising an alert upondetermining that each indicator in the data structure indicates thatfluid was absent from the portion of the medical fluid tube.

In certain implementations, controlling repetitive activation of theultrasonic transmitter includes, for each repetition, activating theultrasonic transmitter for a first period and deactivating theultrasonic transmitter for a second period.

In certain implementations, the first period is less than 10milliseconds.

The certain implementations, the medical fluid tube has an outerdiameter of less than 0.128 inch.

The certain implementations, the medical fluid tube has an innerdiameter of less than 0.031 inch.

In certain implementations, the signal is a measure of voltage.

In certain implementations, the threshold value is a first value iffluid was determined to be present during the previous activation of theultrasonic transmitter, the threshold is a second value if the fluid waspreviously determined to be absent during the previous activation of theultrasonic transmitter, and the first value is greater than the secondvalue.

Implementations can include one or more of the following advantages.

In some implementations, the methods described reduce the number offalse positive alerts caused by small air bubbles passing through amedical fluid tube. The methods described reduce cavitation in themedical fluid tube.

DESCRIPTION OF FIGURES

FIG. 1 is a schematic of a hemodialysis machine that includes a modulardrug delivery device and a drug administration fluid line cassettesecured between a door and inner face of the modular drug deliverydevice. The hemodialysis machine further includes fluid sensorassemblies that can determine whether fluids have been introduced into afluid line engaged with the fluid sensor assemblies.

FIG. 2 is a perspective, exploded view of the drug administration fluidline cassette that is partially illustrated in FIG. 1 and a spike coverthat is disposed over spikes of the drug administration fluid linecassette prior to use.

FIG. 3 is a perspective view of the hemodialysis machine of FIG. 1 withthe door of the drug delivery device opened.

FIGS. 4 and 5 are flow charts depicting methods of detecting fluid lineor fluid tubing installation.

FIG. 6 illustrates a cross sectional view of one or the feeder linesbeing inserted into a central cavity of one the fluid detectors.

FIG. 7 is a schematic illustration of the fluid detector being used todetect air in the feeder line.

FIG. 8 illustrates an example of a fluid detection system.

FIG. 9 is a schematic of a standalone drug delivery system.

FIG. 10 is a perspective view of a modular drug delivery device that isconfigured for use with a single drug vial.

DETAILED DESCRIPTION

In general, the invention relates to methods for detecting whethermedical fluid tubing is correctly installed on a hemodialysis systemand/or controlling repetitive activation of an ultrasonic transmitter toreduce cavitation in fluid within a medical fluid tube. In some aspectsof the invention, a hemodialysis system includes a hemodialysis machinehaving a drug delivery device including one or more pumps and drugdelivery lines connected to a blood circuit. In this way, drug can bedelivered to the blood circuit. A control unit controls aspects of thehemodialysis system, including executing the methods further describedbelow. The control unit is used to determine correct installation of themedical fluid tubing. In some implementations, the medical fluid tubingis too small in diameter (e.g., less than 0.1 inch or less than 0.3inch) to be effectively detected by sensors designed to detect thepresence of conventional, larger medical tubing. By using a combinationof commands provided by the control unit and signals received by thecontrol unit, the control unit can determine whether the tubing has beenproperly installed. The signals received, for example, can be from afluid detector or other sensors that do not directly provide informationregarding the presence of the tube.

Referring to FIG. 1, a hemodialysis system 100 includes a hemodialysismachine 101 that has a drug delivery system 102. The drug deliverysystem 102 includes a modular drug delivery device 103 that is attachedto and exposed on the face of the hemodialysis machine 101 and adisposable drug administration fluid line set (also referred to hereinas a drug administration fluid line cassette) 107 that is connected tothe drug delivery device 103. A drug delivery line (tube) 104 of thedrug administration fluid line cassette 107 is fluidly connected to ablood circuit of the hemodialysis system 100. The blood circuit of thehemodialysis system 100 includes, among other things, a series of bloodlines (tubes) 105, a drip chamber 106, and a dialyzer 110. A blood pump(e.g., a peristaltic pump) 108 is configured to pump blood through theblood circuit during treatment.

The drug delivery device 103 also includes a control unit (e.g., amicroprocessor) that can control various components of the drug deliverydevice 103. As will be described in greater detail below, the controlunit can receive signals from and send signals to the various componentsof the drug delivery device 103. The control unit can control thevarious components of the drug delivery device 103 based on informationreceived from these components to ensure correct installation of thedrug administration fluid line set 107, and to ensure a correct amountof drug is delivered to the patient. In some implementations, forexample, the control unit can receive signals from fluid detectors thatindicate the presence or absence of fluid in the fluid lines. Thecontrol unit can also provide instructions to motors of pumps to drawfluid from drug vials. A combination of these signals and instructionsat appropriate times can enable the control unit to determine whetherthe fluid lines are properly installed.

The hemodialysis system 100 also includes a dialysate circuit andvarious other components that, for the sake of simplicity, will not bedescribed in detail. During hemodialysis treatment, blood is drawn fromthe patient and, after passing through the drip chamber 106, is pumpedthrough the dialyzer 110 where toxins are removed from the blood andcollected in dialysate passing through the dialyzer. The cleansed bloodis then returned to the patient, and the dialysate including the toxins(referred to as “spent dialysate”) is disposed of or recycled andreused. During the hemodialysis treatment, drugs (e.g., Epogen® andVenofer®) are also delivered to the drip chamber 106 using the drugdelivery system 102. The drugs mix with the patient's blood within thedrip chamber 106 and are then delivered to the patient along with thepatient's blood.

Still referring to FIG. 1, the modular drug delivery device 103 includesa drug vial holder 112 configured to hold a single drug vial 116.Another drug vial holder 114 is configured to hold up to three drugvials 118. In the illustrated implementation, the vial 116 furthest tothe left contains Venofer® and the three vials 118 to the right of theVenofer® vial 116 contain Epogen®. Venofer® (iron sucrose injection,USP) is a sterile, aqueous complex of polynuclear iron (III)-hydroxidein sucrose that is manufactured by American Regent, Inc. Venofer® isindicated in the treatment of iron deficiency anemia in patientsundergoing chronic hemodialysis who are receiving supplementalerythropoietin therapy. Epogen® is a drug that stimulates the productionof red blood cells and is also commonly used in dialysis patients.Epogen® is manufactured by Amgen, Inc.

The drug vial holder 112 includes a top member 113 and a bottom member115 that can retain the single Venofer® vial 116 therebetween. Thebottom member 115 has a top surface on which the cap of the invertedVenofer® vial 116 can rest. In certain implementations, the bottommember 115 includes a recess that is sized and shaped to receive a cap(or a portion of the cap) of the vial 116. This recess can help toensure that the vial 116 is properly positioned in the vial holder 112.The bottom member 115 of the drug vial holder 112 also defines a throughopening that allows an associated spike 120 of the drug administrationfluid line cassette 107 (shown in FIG. 2) to pass through the bottommember 113 and pierce a rubber seal of the Venofer® vial 116 during use.

The top and bottom members 113, 115 of the drug vial holder 112 aremoveable relative to one another such that a drug vial can be compressedthere between. In addition, the drug vial holder 112 as a whole ismoveable in the vertical direction relative to the front face of thedrug delivery device 103 and relative to an associated spike 120 of thedrug administration fluid line cassette 107 when the cassette 107 isdisposed in the cassette compartment of the drug delivery device 103. Asa result, when the cassette 107 is disposed in the cassette compartment,the top and bottom members 113, 115 of the drug vial holder 112 can bemoved in unison along with the Venofer® vial 116 to cause the associatedspike 120 of the cassette 107 to pierce the rubber seal of the vial 116.

The drug vial holder 114, which holds the Epogen® vials 118 during use,is similar to the drug vial holder 112 described above. In particular,this drug vial holder 114 also includes top and bottom members 117, 119between which three Epogen® vials 118 can be held, and the bottom member119 defines three openings through which spikes 120 of the cassette 107can pass to pierce rubber seals of the vials 118. In someimplementations, the upper surface of the bottom member 119 definesrecesses that receive the caps of the Epogen® vials 118 and help toensure that the vials 118 are properly positioned in the vial holder114. These recesses can, for example, help to ensure that the vials 118are aligned with the openings in the bottom member 119 to allow thespikes 120 of the cassette 107 to pierce the rubber seals of the vials118.

FIG. 2 illustrates the drug administration fluid line cassette 107 witha protective spike cover 160 removed from the spikes 120. As shown,feeder lines 122 are retained in a spaced apart configuration by a frame166 of the cassette 107. The frame 166 includes along its bottom edge amanifold 168 that connect the feeder lines 122 to the drug delivery line104, two side support members 170, 172 that extend from the manifold168, and a top support member 174 that extends between the two sidesupport members 170, 172. The side support members 170, 172 are attached(e.g., thermally bonded, adhesively bonded, or mechanically attached) attheir bottom and top ends to the manifold 168 and top support member174, respectively. The feeder lines 122 similarly extend between and areattached (e.g., thermally bonded, adhesively bonded, or mechanicallyattached) to the manifold 168 and top support member 174.

In addition to the frame 166, the cassette 107 includes a crossbar 176that extends between the two side support members 170, 172. The crossbar176 includes recessed regions 178 into which the feeder lines 122 arereceived and retained. In addition, hexagonal holes 180 are provided inthe front surface of the cassette 107 (i.e., the surface of the cassette107 that contacts the inner surface of a door 109 of the drug deliverydevice 103 when the cassette 107 is loaded in the cassette compartmentof the drug delivery device 103). As described below, these holes 180mate with hexagonal projections extending from the inner surface of thedoor 109 to secure the cassette 107 to the door 109 during use and tohelp ensure that only appropriate cassettes (e.g., cassettes intendedfor use with the drug delivery device 103 by the drug delivery devicemanufacturer) are used with the drug delivery device 103.

Still referring to FIG. 2, the spikes 120 are attached (e.g., thermallybonded, adhesively bonded, and/or mechanically attached) to and extendupward from the top support member 174 of the cassette 107. The drugvial spikes 120 can be formed of one or more relatively rigid medicalgrade plastics, such as polycarbonate or alphamethylstyrene (AMS), andthe various fluid lines can be formed of a more flexible medical gradeplastic, such as polyvinylchloride (PVC). Each of the spikes 120 caninclude, for example, a central channel that extends along the length ofthe spike and two openings (e.g., channels or slots) along the outersurface of the spike that lead to the central channel. The centralchannel of each spike is aligned with and fluidly connected to avertical passage extending through the top support member 174.

The feeder lines 122 are in fluid communication with their associatedspikes 120 via the vertical passages extending through the top supportmember 174. The feeder lines are also in fluid communication (viaopenings in the top surface of the manifold 168) with the centralpassage that extends through the manifold 168. The drug delivery line104 is similarly connected to the manifold 168 and is in fluidcommunication with the central passage of the manifold 168. Thus, whenthe spikes 120 penetrate the rubber seals of the vials 116, 118 duringuse, drug can flow through the feeder lines 122, the manifold 168, thedrug delivery line 104, and into the drip chamber 106.

The manifold 168, the side support members 170, 172, the top supportmember 174, and the crossbar 176 are typically formed of one or morematerials that are more rigid than the material or materials from whichthe feeder lines 122 are made. Examples of such relatively rigidmaterials include polycarbonate and AMS. However, other relatively rigidmaterials can alternatively or additionally be used. Due to theconstruction and materials of the frame 166 and cross bar 176 of thecassette 107, the feeder lines 122 are held in substantially fixedpositions relative to one another. As a result of this configuration,loading of the drug administration fluid line cassette 107 into thecassette compartment of the drug delivery device 103 is simplified.

Still referring to FIG. 2, the spike cover 160 is a unitary plasticstructure that includes multiple tubular members 162 extending downwardfrom an elongate structure 164. The tubular members 162 form cavities inwhich the drug vial spikes 120 of the cassette 107 are disposed prior totheir insertion into the vials 116, 118. The cavities are sized andshaped so that the portions of the tubular members 162 forming thosecavities grip their associated spikes 120 with sufficient force toprevent the cover 160 from falling off or being inadvertently knockedoff the spikes 120 prior to loading the vials 116, 118 onto the spikes120, while allowing the operator of the system to manually remove thecover 160 from the spikes 120 at the desired time. The spike cover 160is removed from the spikes 120 of the cassette 107 prior to loading thevials 116, 118 onto the spikes 120.

Referring again to FIG. 1, which illustrates the cassette 107 in thecassette compartment of the drug delivery device 103, the spikes 120 ofthe cassette 107 have been inserted into the vials 116 and 118, whichare retained in vial holders 112 and 114, respectively. Peristalticpumps 132 extend from the inner face of the drug delivery device 103 andalign with the feeder lines 122 (between the cross bar 176 and themanifold 168 of the cassette 107) such that when one of the pumps 132 isoperated, the drug is drawn from the vial 116, 118 associated with thatpump and delivered via the feeder lines 122, the manifold 168, and thedrug delivery line 104 to the drip chamber 106 of the blood circuit.

Each of the feeder lines 122 passes through (e.g., is threaded through)a fluid detector 128, arranged in a spaced configuration across theinner face of the drug delivery device 103 above the peristaltic pumps132. The fluid detectors 128 are capable of detecting air bubbles withinthe feeder lines 122. As a result, each of the fluid detectors 128 candetermine whether its associated drug vial 116, 118 is empty duringtreatment, because air is drawn from the vial 116, 118 into the feederline 122 when the vial is empty.

In some implementations, the fluid detectors 128 are ultrasonicdetectors. The AD8/AD9 Integral Ultrasonic Air-In-Line, Air BubbleDetector (manufactured by Introtek International (Edgewood, N.Y.)), forexample, can be used. Other ultrasonic sensors, such as the BD8/BD9Integral Ultrasonic Air Bubble, Air-In-Line & Liquid Level DetectionSensors (also manufactured by Introtek International) can also be used.Similarly, other types of sensors, such as optical sensors, can be usedas the fluid detectors. Examples of such sensors include the OPB 350fluid detector made by Optek. Other types of optical detectors canalternatively or additionally be used.

In some implementations, the fluid detector 128 includes a sensor that,in addition to sensing the presence of an air bubble within itsassociated feeder line 122, can sense the presence of the feeder lineitself. In some implementations, the diameter of the feeder line is toosmall for currently available sensors to reliably detect the presence ofthe feeder line.

The operations of the fluid detectors 128 can be directed by the controlunit of the drug delivery device 103. For example, the control unit mayactivate and deactivate the fluid detectors and process informationprovided by the fluid detectors. In some implementations, the fluiddetectors send signals indicative of the presence or absence of fluid inthe feeder lines 122 to the control unit. The control unit thendetermines, based in part on the signals received from the fluiddetector, whether to raise an alert and/or alarm, as described belowwith respect to FIGS. 6-8.

FIG. 3 illustrates the drug delivery device 103 with the door 109 openedand the drug administration fluid line cassette 107 removed. As shown,the inner surface of the door 109 includes a recessed region 123 that isconfigured to receive the rigid frame 166 of the cassette 107 andelongate slots 124 that are configured to receive the feeder lines 122of the cassette 107 without substantially deforming the feeder lines122. In certain implementations, the recessed region 123 and slots 124are sized so that the frame 166 and feeder lines 122 of the cassette 107can be snapped into the recessed region 123 and slots 124, respectively,and thus releasably secured to the door 109. The inner surface of thedoor 109 also includes the hexagonal projections that are configured fitinto the hexagonal holes 180 formed in the cassette 107 when thecassette 107 is loaded into the door 109. The hexagonal projections canbe sized and shaped to create a snap fit or a snug press fit thatsecures the drug administration fluid line cassette 107 to the door 109.

In addition, the inner surface of the door 109 includes spring-loadedmembers 126 that define recesses or raceways 127 that receive rollermembers of the peristaltic pumps 132 of the drug delivery device 103when the door 109 is closed. Springs are connected to top and bottomregions of each member 126 and to an internal fixed member in the door109 to allow the members 126 to flex in response to contact with therollers of the peristaltic pumps 132 or in response to contact with thefeeder lines 122 positioned between the members 126 and the rollers ofthe peristaltic pumps 132.

Still referring to FIG. 3, the peristaltic pumps 132 are positioned in aspaced configuration across the face of the drug delivery device 103.Each pump 132 includes multiple rollers 133 that compress the associatedfeeder line 122 in a manner to create a “pillow” of fluid (i.e., a“pillow” of air or liquid) that is pinched between two points of thefeeder line 122 that are compressed by the pump rollers 133. The rollers133 are arranged around a circumference of a rotatable frame. As theframe is rotated, the rollers 133 force the “pillow” of fluid throughthe feeder line 122 to the drug delivery line 104. The peristaltic pumps132 are configured to rotate about an axis that extends in a directionthat is substantially parallel to the face of the drug delivery device103. When the cassette 107 is positioned in the cassette compartmentbetween the inner face of the drug delivery device 103 and the closeddoor 109, the feeder lines 122 align with the pumps 132 and are thuspressed into the raceways 127 of the spring-loaded members 126 in thedoor 109. The spring force provided by the springs of the spring-loadedmembers 126 helps to take up tolerance between the raceways 127 and therollers 133, and thus helps to ensure that a fixed compression force isapplied to the feeder lines positioned between the raceways 127 and therollers 133.

During operation of the pump 132, the rollers 133 are rotated from topto bottom (in the view shown in FIG. 3) and thus force pillows of fluiddownward through the associated feeder line 122. When the pump 132 isbeing operated, vacuum pressure is applied to the drug vial 116, 118that is connected to the feeder line 122. In certain cases, the initialpressure in the drug vial 116, 118 is equal to the ambient pressure, andwhen all of the drug has been delivered, the ending pressure within thevial is less than ambient pressure (e.g., about −10 psi). In otherwords, the pressure within the drug vial 116, 118 progresses fromambient to the negative pressure as the drug is delivered. The pump 132is configured to generate a vacuum pressure within the feeder line 122that exceeds the competing vacuum within the drug vial 116, 118. As aresult, the drug is drawn from the vial 116, 118, through the drug vialspike 120 and into the feeder line 122.

The spacing of the rollers 133 about the circumference of the rotatableframes 130 of the peristaltic pumps 132 is selected so that at least oneof the rollers 133 is positioned in the raceway 127 of the associatedspring-loaded member 126 when the door 109 of the drug delivery device103 is closed. This helps to ensure that the feeder lines 122 positionedbetween the pumps 132 and the raceways 127 are always occluded in atleast one location and thus helps to prevent the drugs from passingthrough the feeder lines 122 to the manifold 168 when the pumps 132 arenot in operation.

Referring again to FIGS. 1-3, the drug vial holders 112, 114 of the drugdelivery device 103 can be equipped with various types of sensors forsensing the presence of a vial, identifying the type of drug vialinstalled, detecting the size of the drug vials, and/or detecting themass of the drug vials. In some implementations, each drug vial holder112, 114 includes a sensor to sense the presence of a vial or drugcontainer. In certain implementations, each drug vial holder 112, 114includes a system which identifies the drug vial installed. The drugvial identification system can, for example, include a bar code readerthat reads bar codes on the vials. Different types of sensors canalternatively or additionally be used. In some implementations, forexample, the vial identification system uses RFID technology. Otherexamples of suitable sensors include color sensors for sensing the colorof color-coded drug vials and/or for sensing the color of the drugwithin the vial, photo sensors (e.g., cameras) that are equipped withtext recognition software to read text on the drug vial, capacitivesensors that permit different size vials to be detected, load cells orscales that detect the mass of the vial, and conductivity or electricalimpedance sensors that can be used to determine the type of drug withinthe vial.

The sensors can communicate with the control unit, sending detectedinformation to the control unit and receiving commands from the controlunit. The control unit can also control the pumps 132 to ensure thatonly one of the pumps 132 is in operation at a time. This helps toensure that drug is pulled from only one of the vials 116, 118 at a timeduring treatment. Upon determining that the prescribed volume of thedrug has been delivered (based on monitoring the operation of the pumps132), the control unit can turn off the pump 132 associated with thatdrug vial 116, 118 and turn on the pump 132 associated with the drugvial 116, 118 containing the next drug to be delivered. In addition,after the full contents of a vial have been evacuated, air will besucked into the feeder line 122 associated with that vial and will bedetected by the fluid detector 128. In response, the control unit canturn off the pump 132 associated with the empty vial and turn on thepump 132 associated with the vial containing the next drug to bedelivered.

The control unit can also control certain components of the drugdelivery device 103 based on signals received from the drug vial IDsensors, which indicate the presence of a vial and/or the identity ofthe vial contents. Such an arrangement can help to ensure that thecorrect vials (e.g., the correct number of vials and the vialscontaining the correct contents) are used for the treatment. Uponreceiving signals from the drug vial ID sensors that do not match theinputted treatment information, for example, an alarm (e.g., an audibleand/or visual alarm) can be activated. Alternatively or additionally,the drug delivery device 103 can be configured so that treatment cannotbe initiated until the sensors detect the correct combination of vials.

The drug delivery device 103 (e.g., the control unit of the drugdelivery device 103) is configured to sense if the blood pump 108 of thedialysis machine 101 is running and to pause drug delivery if the bloodpump 108 is stopped. This technique prevents “pooling” of the delivereddrug in the drip chamber 106 during treatment.

Still referring to FIGS. 1-3, the drug delivery device 103 furtherincludes a user interface 134 that is connected to the control unit. Theuser interface 134 includes keys that allow the user to navigate throughdisplays associated with the vials 116, 118 and set the desired dosagefor each of the vials 116, 118. In addition, the user interface 134includes start and stop keys that allow the user to start and stop thedrug delivery device 103.

Any of various other types of user interfaces can alternatively oradditionally be used. In some implementations, the drug delivery deviceincludes a user interface that allows the user to select a drug toinfuse from a menu. In certain implementations, the user may confirmthat the drug identified by the drug vial ID sensor is correct and/ormake appropriate adjustments. The user interface can be used to inputand/or monitor various different treatment parameters. Examples of suchparameters include drug dosage, drug delivery rate, amount of drugdelivered, status of the drug delivery for each drug channel, time,percent complete, percent remaining, time remaining, time delivered,date, patient ID, patient name, alarms, alerts, etc. Such userinterfaces can include a color graphical display. In certainimplementations, for example, the user interface is color codedaccording to drug, dosing, or status of drug delivery (e.g., done,running, ready, etc.).

The hemodialysis machine 101 also includes an alarm and/or alert systemto which the control unit of the hemodialysis machine 101 is connected.The alarm and/or alert system can be configured to emit a visual and/oraudio alarm and/or alert. The alarm and/or alert system can furtherinclude pre-programmed alarm and/or alert limitations so that when auser modifies any aspect of the system to be outside of the limitations,or the machine itself detects any aspects of the system to be outside ofthe limitations, the module emits an alarm and/or alert.

Still referring to FIGS. 1-3, a method of using the hemodialysis system100 to perform hemodialysis on a patient will now be described. Prior tobeginning hemodialysis treatment on a patient, the various lines thatmake up the blood circuit and dialysate circuit of the hemodialysismachine are primed, and then the patient lines 105 are connected to thepatient. After connecting the patient lines 105 to the patient, theblood pump 108 is activated to circulate blood through the bloodcircuit. A dialysate pump is also activated to pump dialysate throughthe dialysate circuit of the hemodialysis machine. The blood is drawnfrom the patient and delivered to the drip chamber 106 via the arterialpatient line. The drip chamber 106 acts as an air trap such that any airin the blood is released as the blood passes through the drip chamber106. In particular, the drip chamber 106 includes a vent through whichair released from the blood can be vented from the drip chamber 106. Theblood is then pumped from the drip chamber 106 to the dialyzer 110,which includes a semi-permeable membrane that divides the dialyzer 110into two chambers. As the blood passes through one of the chambers ofthe dialyzer 110, dialysate from the dialysate circuit passes throughthe other chamber. As the blood flows by the dialysis fluid, impurities,such as urea and creatinine, diffuse through the semi-permeable membraneinto the dialysate. The spent dialysate is either disposed of orrecycled and reused. The cleansed blood exiting the dialyzer 110 isreturned to the patient via the venous patient line.

After initiating the hemodialysis treatment, the operator of thehemodialysis system 100 (e.g., the physician, nurse, medical assistant,or patient) determines the prescribed Epogen® dose and then consults adosing schedule for the different vial combinations that can be used todeliver the prescribed Epogen® dose. Examples of dosing schedules aredescribed in U.S. patent application Ser. No. 12/827,119, which isherein incorporated by reference in its entirety. The operator thenselects one of the Epogen® vial combinations provided based on theoperator's preference and loads the selected Epogen® vials into the drugvial holders. The operator also loads a vial of Venofer® into one of thedrug vial holders. In some implementations, the operator selects fromvarious Venofer® vials that are the same size but contain differentamounts of Venofer®.

The operator of the system then connects the disposable drugadministration fluid line cassette 107 to the inner surface of the door109 by inserting the frame 166 and feeder lines 122 into theircorresponding recessed regions 123 and slots 124. As a result of this,the hexagonal shaped projections that extend from the inner surface ofthe door 109 slide into the matching holes 180 formed in the frame 166of the drug administration fluid line cassette 107. The matingengagement of the hexagonal shaped projections and openings 180, alongwith the snap fit of the cassette frame 166 and feeder lines 122 intotheir corresponding recessed regions 123 and slots 124, helps ensurethat the cassette 107 remains securely fixed to the door 109. Inaddition, the unique hexagonal shape of the projections and openings 180can help to ensure that only drug administration fluid line cassettesintended for use with the drug delivery device 103 can be used. Forexample, drug administration fluid line cassettes that do not includeholes capable of receiving the hexagonal projections of the door 109could not be properly secured to the door 109. This would indicate tothe operator that an incorrect cassette was loaded into the cassettecompartment of the drug delivery device 103 and, in many cases, willprevent the door 109 from shutting and thus prevent the drug deliverydevice 103 from being operated with that cassette.

After loading the drug administration fluid line cassette 107 onto thedoor 109, the operator closes the door 109 and secures a latch 167 tohold the door 109 in the closed position. Because the cassette 107 issecurely fastened to the door 109 in a desired position, the feederlines 122 align with their associated pumps 132 and fluid detectors 128when the door 109 is closed. Thus, as the door 109 is closed, theprotruding peristaltic pumps 132 press the feeder lines 122 into theraceways 127 formed along the inner surface of the door 109, and theinner surface of the door 109 presses the feeder lines 122 intoengagement with the fluid detectors 128. With the door 109 in the closedposition, the spikes 120 of the cassette 107 rest directly below theholes formed in the bottom members 115, 119 of the vial holders 112,114.

The prescribed dosages of Venofer® and Epogen® are then entered into thedrug delivery device 103 using the user interface 134 of thehemodialysis machine 101 with which the control unit of the drugdelivery device 103 is in communication. Alternatively or additionally,the prescribed dosage of Venofer® and Epogen® can be electronicallytransmitted to the control unit of the drug delivery device 103 from adevice, such as a portable computing device, or from a database orwebsite accessible by the patient's prescribing physician. The operator,after reviewing the prescribed dosage entered into or transmitted to themachine, confirms that the prescribed dosage is correct by pressing abutton (e.g., an “Accept” or “Confirm” button) on the user interface 134of the hemodialysis machine 101, which initiates the spiking and primingprocess.

Referring also now to FIG. 4, after spiking the vials 116, 118, themachine determines whether the feeder lines 122 have been properlyinstalled. The process (400) for determining whether the feeder lines122 have been properly installed installation begins (402) and a signalfrom the fluid detector 128 is received (404) by the control unit. Ifthe received signal indicates fluid detected, the system provides afluid detected error (406). The fluid detected error can be an alert oran alarm provided by the system. The fluid detected error can be aresult of wet feeder lines 122, for example, if there is moisture on theoutside of the feeder lines 122. The fluid detected error can also be aresult of an oversensitive fluid detector 128. The operator can check toensure there is no moisture or fluid on or in the feeder lines 122 andrestart the process 400. If the fluid detected error still triggers, thefluid detector 128 may be oversensitive or faulty and need replacement.By receiving a signal from the fluid detector 128 before fluid is pumpedfrom the vials 116, 118, the fluid detector 128 can be calibrated orchecked for proper functioning. One advantage of checking for properfunctioning of components prior to pumping fluid from the vials 116, 118is that problems can be addressed without wasting any drug.

If the signal received from the fluid detector 128 indicates no fluid, asignal is received from a door sensor (408) by the control unit. Thedoor sensor is a sensor on the door 109 or the latch 167 of the door 109that detects whether the door 109 is properly closed. If the signalreceived from the door sensor indicates the door 109 is open, the systemprovides a door open error (410). The door open error can be an alert oran alarm provided by the system. The operator can ensure there are noobstructions (such as the feeder lines 122) preventing the door fromclosing properly. Once the door 109 is properly closed, the operator cancontinue or restart the process 400.

If the signal received from the door sensor indicates the door isproperly closed, an instruction is provided by the control unit for amotor (412) of the pump 132. The instruction directs the motor to pumpthe drug from the vial fluidly connected to the pump 132. By activatingthe pumps 132, either sequentially or simultaneously, the feeder lines122 of the drug administration fluid line cassette 107 are primed,causing a portion of the drug to be drawn from each of the vials 116,118. After a period of time passes after providing the instruction, asignal is received by the control unit from the fluid detector 128(414). The period of time can be a period of time required under normaloperating conditions for the feeder lines 122 to be primed, or for thedrug to reach the pump 132. If the signal received from the fluiddetector 128 at this point indicates no fluid detected in the feederline 122, it is determined that the tube is installed incorrectly (416).The system can provide an alarm or alert to indicate an incorrect tubinginstallation to the user. If the signal received from the fluid detector128 indicates fluid is detected, then the tubing is correctly installedand the process can end (418) and the pump 132 is stopped and pinchesoff or occludes the feeder line 122.

After priming the feeder lines 122, Venofer® is delivered from theVenofer® vial 116 to the drip chamber 106 by activating the pump 132associated with the Venofer® vial 116 (while leaving all of the otherpumps off). The pump 132 delivers all of the Venofer® in the vial 116unless an error is detected. A possible error that can be detected isthe incorrect installation of the tube, for example, by the process(500) depicted in FIG. 5.

Still referring to FIG. 5, while delivering the Venofer® to the dripchamber 106 via the feeder line 122, the control unit receives a firstsignal from the fluid detector (502). The first signal can be receivedafter the priming of the feeder lines 122. The first signal is a signalindicating the presence of fluid in the tube. For example, a voltagemagnitude of the signal (e.g., greater than 0.05 volts peak to peak whenmeasured directly from the receive element) can indicate that fluid ispresent. The magnitude of the first signal is determined (504) andstored. The magnitude of the first signal is used as a baselinemeasurement against which later signals are measured. Using themagnitude of the first signal to compare later signals, rather than afixed, or even adjustable, predetermined magnitude can allow fordiscrepancies between different fluid detectors 128 and drug deliverydevices 103.

Instruction for the motor to pump (or continue pumping) the drug isprovided (506) by the control unit. The instruction is provided to themotor to pump the drug for delivery of the drug to the patient. A secondsignal is received from the fluid detector (508). The second signal isreceived at a time later than the first signal. The pump 132 is activeduring the time between the first and second signals, as the instructionis provided to the motor. A magnitude of the second signal is determined(510).

The magnitudes of the first and second signals are compared (512). Ifthe difference between the two signals is greater than a thresholdamount or greater than or equal to the threshold amount, the tubing isincorrectly installed (514). For example, in some implementations, anamplified and filtered signal presented to an A/D voltage difference ofbetween 0.250-0.500V can be used as the threshold amount. With anincorrectly installed tubing, such as a tubing occluded by the door 109of the drug delivery device 103 improperly closed on the tubing, thefluid is unable to properly flow through the tubing. With an occlusionin the tubing, the fluid builds up at the point of occlusion, which canresult in an expansion of the tube at the point of occlusion and anincreased volume of fluid in the tube. The increased volume of fluid canresult in a signal from the fluid detector 128 that is greater than anormal range. Thus, incorrectly installed tubing can be determined by asecond signal with a magnitude greater than a first signal by athreshold amount.

If the magnitude of the second signal is not greater than the magnitudeof the first signal, the control unit can continue to receive signalsfor comparison. The comparisons can continue to be made to the firstsignal, or alternatively, the second signal can be used as a newbaseline measure. In some implementations an average or othercombination of the magnitudes of the first and second signals can beused. In some implementations, one of the two signals is chosen by somecriteria as the baseline measurement. For example, the signal with thelower magnitude can be used for future comparisons. The comparisons cancontinue throughout the drug delivery process, or only for a certainperiod of time during the delivery.

The pump associated with the first Epogen® vial 118 (i.e., the Epogen®vial directly to the right of the Venofer® vial 116) is then activatedsuch that Epogen® is delivered to the drip chamber 106. A similarprocess as described above can be used to determine whether the feederline 122 associated with the first Epogen® vial is properly installed.After confirming proper installation, Epogen® is pumped. When the fluiddetector 128 detects air in the feeder line 122, a signal is sent to thecontrol unit, indicating that the first Epogen® vial 118 is empty. Thecontrol system then sends a signal causing the pump associated with thefirst Epogen® vial 118 to be turned off after assuring that anadditional known volume is pumped so that the Epogen® in the linedownstream of the fluid detector 128 is flushed down to a segment wherethe delivery of drug from the next vial can push that Epogen® remainingin the line to the drip chamber 106. In particular, the control unitensures that the additional pumped volume is sufficient to push theEpogen® past the pump 132 and into the passage of the manifold 168 suchthat the next volume of drug delivered will push the Epogen® to the dripchamber 106. The control unit also sends a signal to activate the pump132 associated with the second Epogen® vial 118 (i.e., the Epogen® vialdirectly to the right of the first Epogen® vial). The Epogen® deliveryprocess described above is then repeated for the second and thirdEpogen® vials.

After delivering the desired amounts of Venofer® and Epogen® to the dripchamber 106, the drug delivery device 103 is deactivated and the drugadministration fluid line cassette 107 and vials 116, 118 are removedfrom the drug delivery device 103 and discarded.

Each of the fluid detectors 128 can be part of a fluid detection systemthat is configured to determine if any of the vials 116, 118 are emptyby analyzing the presence or absence of fluid in the feeder tubes 122.

FIG. 6 illustrates a cross sectional view of one or the feeder lines 122being inserted into a central cavity of one the fluid detectors 128. Afeeder line 122 is placed adjacent to a fluid detector 128. The feederline 122 typically has an outer diameter of less than or equal to 0.25inch. For example, the feeder line 122 may have an outer diameter of0.125 inch plus or minus 0.003 inch. The feeder line 122 typically hasan inner diameter 604 of less than or equal to 0.05 inch. For example,the feeder line 122 may have an inner diameter of 0.03 inch plus orminus 0.001 inch.

The fluid detector 128 includes the cavity 612 which allows the feederline 122 to be positioned between an ultrasonic sensor transmitter 608and an ultrasonic sensor receiver 810. The cavity 612 in the fluiddetector 128 for the feeder line 122 may be smaller than the outerdiameter of the feeder line 122 so that the medical fluid tube must bedeformed in order to fit into the allotted space. For example, the outerdiameter of the feeder line 122 may be about 0.025 inch greater than thewidth of the cavity 612. In some implementations, the outer diameter ofthe feeder line 122 is about 0.125 inch and the width of the cavity 612is about 0.1 inch.

When the feeder line 122 is inserted into the cavity 612 of the fluiddetector 128, the relative size of the cavity 612 and the feeder line122 causes a distortion in the shape of the feeder line 122. Thedistorted feeder line 122 applies pressure to the fluid detector 128 andthe pressure holds the feeder line 122 in position.

The ultrasonic sensor transmitter 608 and the ultrasonic sensor receiver610 are positioned within the housing of the fluid detector 128.Ultrasonic signals are transmitted from the ultrasonic sensortransmitter 608 and are received by the ultrasonic sensor receiver 610.The presence of fluid in the interior 604 of the feeder line 122 can bedetermined based on the strength of the ultrasonic signal received bythe ultrasonic sensor receiver 610. The ultrasonic sensor receiver 610transforms the ultrasonic signal into voltage. The resulting voltagewill be higher when fluid is present in the feeder line 122 and lowerwhen it is not.

The ultrasonic signal being transmitted from the ultrasonic sensortransmitter 608 to the ultrasonic sensor receiver 610 can causecavitation, the formation of small bubbles within the fluid in thefeeder line 122. The accumulation of these air bubbles can affect thetransmission of the ultrasonic signal through the feeder line 122 andconsequently affect the voltage provided by the ultrasonic sensorreceiver 610, as described below.

FIG. 7 is a schematic illustration of the fluid detector 128 being usedto detect air in the feeder line 112. As discussed above, inserting thefeeder line 122 into the fluid detector 128 can cause a distortion inthe medical fluid tube 122.

As the ultrasonic sensor transmitter 608 continuously transmitsultrasonic energy through the feeder line 122, the ultrasonic energy cancause the formation of air bubbles 720 (i.e. cavitation) within thefluid in the interior 604 of the feeder line 122. The air bubbles 720tend to accumulate and form an air pocket 724 between the ultrasonicsensor transmitter 608 and the ultrasonic sensor receiver 610.

As more air accumulates in the feeder line 122, the voltage provided bythe ultrasonic sensor receiver 610 in response to the ultrasonic energyreceived from the ultrasonic transmitter 608 declines. This declinemakes it difficult to determine if medical fluid is flowing through thefeeder line 122. For example, a low voltage reading may be caused by acollection of air bubbles caused by cavitation or may be caused by theabsence of fluid in the medical fluid tube.

To mitigate cavitation in the feeder line 122, the ultrasonic sensortransmitter 608 can be repetitively activated to reduce (e.g., minimize)the accumulation of air bubbles within the feeder line 122. For example,the ultrasonic sensor transmitter 608 can be active for 5 ms andinactive for 995 ms. The ultrasonic transmitter can alternatively beactive for other periods. For example, the ultrasonic sensor may beactive for a period of 2-15 ms and subsequently inactive for 998 to 985ms. A reading can be taken from the ultrasonic sensor receiver 610 atany point during which the ultrasonic sensor transmitter 608 istransmitting. In some implementations, a reading is taken near the endof the transmission by the ultrasonic sensor transmitter. For example, areading may be taken from the ultrasonic transmitter receiver 610 4 msinto a 5 ms transmission by the ultrasonic sensor transmitter 608.

The effect of cavitation can be further mitigated by taking multiplereadings before determining there is a lack of fluid in the feeder line122 and transmitting a signal to that effect. For example, the systemmay not signal a lack of fluid in the feeder line 122 until fluid hasbeen absent for three consecutive seconds.

FIG. 8 illustrates an example of a fluid detection system. A controlunit 802 can include a set of drive parameters 804. The drive parameters804 can be stored in persistent memory (for example, flash memory ormagnetic storage) or can be stored in volatile memory such as randomaccess memory. The drive parameters 804 specify operations of the fluiddetection system. For example, the drive parameters 804 can specify aperiod during which an ultrasonic sensor transmitter 608 is to transmit(transmit time), a period of time the ultrasonic sensor transmitter isto wait until the next transmission (wait time), a time when a readingis to be taken from the ultrasonic sensor receiver (read time), and athreshold value which is used to determine if fluid is detected.

The transmit time and the wait time defines a duty cycle. For example,the duty cycle can be 1 second long. The read time may be definedrelative to the transmit time or the duty cycle.

Based on the parameter values, the control unit 802 causes the sensordriving process 806 to send a signal to the ultrasonic sensortransmitter 608. In some implementations, the signal is a 2.5 Mhz drivesignal. The ultrasonic sensor receiver element 610 receives a signaltransmitted by the transmitting ultrasonic sensor 608. The signal isamplified and filtered 812 to produce a clear signal. The clear signalis converted to a digital signal using an analog digital converter 814.

The fluid detector 816 receives the digital signal. At the timespecified by the drive parameters 804, the fluid detector 816 comparesthe value of the digital signal to a threshold value to determine iffluid is detected. In some implementations, the fluid detectordetermines if fluid was detected during the previous cycle. If fluid wasdetected during the previous cycle, the fluid detector compares thedigital signal to a first threshold value. If fluid was not detected,the fluid detector compares the digital signal to a second thresholdvalue. For example, if fluid was previously detected, the fluid detectormay determine that fluid is not currently detected if the digital signalis below 2050 mV. If fluid was not previously detected, the fluiddetector may determine that fluid is not currently detected if thedigital signal is below 2100 mV. In some implementations, the thresholdsare calibrated based on experimental performance of the ultrasonicsensors. The fluid detector stores the most recently received signal inan internal register.

Intermittently, the fluid detector determines whether or not fluid isdetected during the most recent duty cycle, the fluid detector storesthe value in a stored value repository 820. The stored value repositorycan maintain a number of historic readings. For example, the storedvalue repository may store an indicator of the last 3, 4, 5, or 6 storedvalues.

An alert component 818 signals an alert and/or alarm condition if all ofthe historic readings in the stored values repository 820 indicate thatno fluid was detected. For example, if no fluid is detected every 500 msfor 3 seconds (for a total of six readings), then the alert component818 signals the alert and/or alarm condition. By waiting until no fluidhas been detected in the feeder line 122 for 3 seconds, the number offalse alarms are reduced. For example, a small air bubble passingthrough the feeder line 122 will not trigger an alert or alarm. Thealarm alerts an operator if the vials are empty of medical fluid andneed to be replaced.

While certain drug delivery devices described herein are provided ascomponents of hemodialysis systems, the drug delivery devices can beused in any type of medical device that would benefit from drug infusioncapabilities. Alternatively, the drug delivery devices described hereincan be configured to be operated as stand alone machines (i.e., notconnected to another medical device). FIG. 9 illustrates a stand alonedrug delivery device 902, which is substantially the same as the drugdelivery device 103 described above but sits on a wheeled cart 960. Thedrug delivery line 104 of this stand alone drug delivery device 902 isconnected to a drip chamber. During use, the drug(s) is/are deliveredfrom the vials 116, 118 to the drip chamber 962. The drug(s) is/are thendelivered from the drip chamber 962 to the patient via a fluid line 964.The drip chamber 962, similar to the above-described drip chamber 106,helps to ensure that any air pulled into the system from the vials doesnot reach the patient. The drug delivery device 902 can be used in amanner similar to the drug delivery device 103 described above todeliver drugs to a patient and similar processes can be used todetermine proper installation of medical fluid tubes 922.

While the drug vial holders 112, 114 are described as automaticallyspiking the vials 116, 118, manually spiking devices can alternative oradditionally be used. For example, the Venofer® and Epogen® vial can beindividually inserted into the drug vial holder 114 and manually appliedto the spikes 120 of the cassette 107.

While the feeder lines 122 are described as being included in a cassette107, the feeder lines 122 can also or additionally be separate lines,each line attached to a vial 116, 118. The feeder lines 122 can bemanually positioned in the fluid detectors 128.

While the feeder lines 122 are described as being held in the housing ofthe fluid detector 128 by use of pressure, other methods may also beused to hold the feeder line 122 in position, for example, clips.

While the system is described as not signaling a lack of fluid in thefeeder line 122 until fluid has been absent for three consecutiveseconds, the duration of time that the system waits prior to signaling alack of fluid may vary based on an expected state of the fluid in thefeeder line 122. For example, when the feeder line is newly insertedinto the fluid detector, the system may signal a lack of fluid each timea reading is beneath the threshold. During a period of time when medicalfluid is being delivered to the patient, the system may not signal alack of fluid in the feeder line 122 until fluid has been absent forthree consecutive seconds. When the medical fluid delivery is nearingcompletion (e.g., the medical fluid has been pumped for predeterminedperiod of time associated with complete delivery of the medical fluidfrom the vial), the system may signal a lack of fluid each time areading is beneath the threshold.

While the fluid detector 816 is described as comparing the digitalsignal to threshold values, in some implementations, the thresholdvalues may vary based on an expected state of the fluid in the feederline 122. For example, when the feeder line is newly inserted into thefluid detector, the threshold may be increased, for example, by 100 mV,so that fluid is not detected if the digital signal is less than 2200mV. When the feeder line is completely inserted and during a period oftime when medical fluid is being delivered to the patient, the fluiddetector 816 may compare the digital signal to a lower threshold value.For example, during delivery to the patient, fluid is not detected onlyif the digital signal is less than 2100 mV. When the medical fluiddelivery is nearing completion, (e.g., the medical fluid has been pumpedfor predetermined period of time associated with complete delivery ofthe medical fluid from the vial), the fluid detector may compare thedigital signal to a higher threshold value, for example, 2200 mV.

FIG. 10 illustrates a modular drug delivery device 1002 configured toretain only a single vial detached from the hemodialysis machine. Thedrug delivery device 1002 is substantially the same as the drug deliverydevice 103 described above. However, the drug delivery device 1002illustrated in FIG. 10 includes a drug vial holder that includes onlyone channel 1014 instead of four. In addition, the drug administrationfluid line set 107 that is used with the drug delivery device 1002includes a single drug delivery line 1004 that is connected to the vial118 via the drug vial spike 120. Similar process as described above canbe used to determine proper installation of the single drug deliveryline 1004, using fluid detector 128. The drug delivery device 1002 canbe used where only one drug (e.g., Epogen®) is being administered to thepatient and the prescribed dosage of that drug can be achieved with asingle vial.

While drug delivery devices have been described above as including theirown control unit, the drug delivery device can alternatively oradditionally be configured to communicate with a control unit of thehemodialysis machine. In certain implementations, for example, thevarious components of the dialysis machine, including the drug deliverydevice components, are controlled by a single control unit of thehemodialysis machine.

While the pump has been described above to stop and occlude the feederlines after priming the feeder lines, the drug delivery process can beconfigured to continue pumping after priming. For example, in certainimplementations, the priming can be an initial part of a continuous drugdelivery process.

While the process of detecting incorrect installation of the tubing bycomparing signals from the fluid detector has been described above tostart after priming the feeder lines, the process can start during thepriming of the feeder lines. In certain implementations, for example,the first signal can be received during priming. The second signal canalso be received during priming, or alternatively, after priming. Theprocess can continue throughout the drug delivery process, so thatsecond signals are received periodically through the duration of thedrug delivery. In some implementations, the process can be stopped aftera certain time.

While the methods of operating the drug delivery devices described aboveinvolve the user inputting a desired dosage prescription into the drugdelivery device (e.g., typing the prescription into the touch screen ofthe drug delivery device), the prescription can alternatively betransmitted to the drug delivery device electronically. In certainimplementations, for example, the desired prescription can be determinedby a physician of the patient to be treated and the physician can inputthe prescription into a secured database or website. The prescriptioncan then be automatically transmitted from the database to the controlunit of the drug delivery device (e.g., to the control unit of thedialysis machine of which the drug delivery device is a part). Thistechnique can help to prevent prescription input errors by the operatorof the drug delivery device.

While drug vials have been described as being used in the drug deliverysystems and methods described above, in certain implementations, othertypes of drug containers, such as bags, bottles, etc., are used.

While the drug delivery devices above have been described as being usedto deliver Venofer® and/or Epogen®, it should be understood that theterm “drug” as used herein incorporates pharmaceuticals as well as otherfluids delivered to a patient intravenously. Other drugs that arecontemplated to be automatically delivered to the patient in accordancewith the various implementations of the invention, include but are notlimited to, phosphate binders, vitamin D, and anticoagulants.

Implementations of the subject matter and the operations described inthis specification can be implemented in digital electronic circuitry,or in computer software, firmware, or hardware, including the structuresdisclosed in this specification and their structural equivalents, or incombinations of one or more of them. Implementations of the subjectmatter described in this specification can be implemented as one or morecomputer programs, i.e., one or more modules of computer programinstructions, encoded on computer storage medium for execution by, or tocontrol the operation of, data processing apparatus. Alternatively or inaddition, the program instructions can be encoded on an artificiallygenerated propagated signal, for example, a machine-generatedelectrical, optical, or electromagnetic signal, that is generated toencode information for transmission to suitable receiver apparatus forexecution by a data processing apparatus. A computer storage medium canbe, or be included in, a computer-readable storage device, acomputer-readable storage substrate, a random or serial access memoryarray or device, or a combination of one or more of them. Moreover,while a computer storage medium is not a propagated signal, a computerstorage medium can be a source or destination of computer programinstructions encoded in an artificially generated propagated signal. Thecomputer storage medium can also be, or be included in, one or moreseparate physical components or media (for example, multiple CDs, disks,or other storage devices).

The operations described in this specification can be implemented asoperations performed by a data processing apparatus on data stored onone or more computer-readable storage devices or received from othersources.

The term “data processing apparatus” encompasses all kinds of apparatus,devices, and machines for processing data, including by way of example aprogrammable processor, a computer, a system on a chip, or multipleones, or combinations, of the foregoing The apparatus can includespecial purpose logic circuitry, for example, an FPGA (fieldprogrammable gate array) or an ASIC (application specific integratedcircuit). The apparatus can also include, in addition to hardware, codethat creates an execution environment for the computer program inquestion, for example, code that constitutes processor firmware, aprotocol stack, a database management system, an operating system, across-platform runtime environment, a virtual machine, or a combinationof one or more of them. The apparatus and execution environment canrealize various different computing model infrastructures, such as webservices, distributed computing and grid computing infrastructures.

A computer program (also known as a program, software, softwareapplication, script, or code) can be written in any form of programminglanguage, including compiled or interpreted languages, declarative orprocedural languages, and it can be deployed in any form, including as astandalone program or as a module, component, subroutine, object, orother unit suitable for use in a computing environment. A computerprogram may, but need not, correspond to a file in a file system. Aprogram can be stored in a portion of a file that holds other programsor data (for example, one or more scripts stored in a markup languagedocument), in a single file dedicated to the program in question, or inmultiple coordinated files (for example, files that store one or moremodules, sub programs, or portions of code). A computer program can bedeployed to be executed on one computer or on multiple computers thatare located at one site or distributed across multiple sites andinterconnected by a communication network.

The processes and logic flows described in this specification can beperformed by one or more programmable processors executing one or morecomputer programs to perform actions by operating on input data andgenerating output. The processes and logic flows can also be performedby, and apparatus can also be implemented as, special purpose logiccircuitry, for example, an FPGA (field programmable gate array) or anASIC (application specific integrated circuit).

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processors of any kind of digital computer. Generally, aprocessor will receive instructions and data from a read only memory ora random access memory or both. The essential elements of a computer area processor for performing actions in accordance with instructions andone or more memory devices for storing instructions and data. Generally,a computer will also include, or be operatively coupled to receive datafrom or transfer data to, or both, one or more mass storage devices forstoring data, for example, magnetic, magneto optical disks, or opticaldisks. However, a computer need not have such devices. Moreover, acomputer can be embedded in another device, for example, a mobiletelephone, a personal digital assistant (PDA), a mobile audio or videoplayer, a game console, a Global Positioning System (GPS) receiver, or aportable storage device (for example, a universal serial bus (USB) flashdrive), to name just a few. Devices suitable for storing computerprogram instructions and data include all forms of nonvolatile memory,media and memory devices, including by way of example semiconductormemory devices, for example, EPROM, EEPROM, and flash memory devices;magnetic disks, for example, internal hard disks or removable disks;magneto optical disks; and CD ROM and DVD-ROM disks. The processor andthe memory can be supplemented by, or incorporated in, special purposelogic circuitry.

To provide for interaction with a user, implementations of the subjectmatter described in this specification can be implemented on a computerhaving a display device, for example, a CRT (cathode ray tube) or LCD(liquid crystal display) monitor, for displaying information to the userand a keyboard and a pointing device, for example, a mouse or atrackball, by which the user can provide input to the computer. Otherkinds of devices can be used to provide for interaction with a user aswell; for example, feedback provided to the user can be any form ofsensory feedback, for example, visual feedback, auditory feedback, ortactile feedback; and input from the user can be received in any form,including acoustic, speech, or tactile input. In addition, a computercan interact with a user by sending documents to and receiving documentsfrom a device that is used by the user; for example, by sending webpages to a web browser on a user's client device in response to requestsreceived from the web browser.

While this specification contains many specific implementation details,these should not be construed as limitations on the scope of anydisclosures or of what may be claimed, but rather as descriptions offeatures specific to particular implementations of particulardisclosures. Certain features that are described in this specificationin the context of separate implementations can also be implemented incombination in a single implementation. Conversely, various featuresthat are described in the context of a single implementation can also beimplemented in multiple implementations separately or in any suitablesubcombination. Moreover, although features may be described above asacting in certain combinations and even initially claimed as such, oneor more features from a claimed combination can in some cases be excisedfrom the combination, and the claimed combination may be directed to asubcombination or variation of a subcombination.

What is claimed is:
 1. A dialysis system comprising: a dialysis machine;a control unit; a medical fluid tube connected to the dialysis machine;an ultrasonic transmitter positioned adjacent to the medical fluid tube;an ultrasonic receiver positioned adjacent to the medical fluid tubeconfigured to receive one or more signals in response to the activationof the ultrasonic transmitter; and a computer storage medium encodedwith computer program instructions that when executed by the dialysissystem, causes the dialysis system to perform operations comprising:controlling repetitive activation of the ultrasonic transmitter, whereincontrolling repetitive activation of the ultrasonic transmittercomprises, for each repetition: activating the ultrasonic transmitterfor a first period of 2 to 15 milliseconds; and deactivating theultrasonic transmitter for a second period of 998 to 985 milliseconds;receiving a signal from the ultrasonic receiver during an activation ofthe ultrasonic transmitter; and determining that fluid is absent orpresent in a portion of the medical fluid tube based on a comparisonbetween the signal and a threshold value.
 2. The system of claim 1,wherein the computer storage medium is further encoded with computerprogram instructions that when executed by the dialysis system, causesthe dialysis system to perform operations comprising: storing anindicator of the absence or presence of fluid in a data structure, thedata structure storing a plurality of indicators determined duringprevious activations of the ultrasonic transmitter.
 3. The system ofclaim 2, wherein the computer storage medium is further encoded withcomputer program instructions that when executed by the dialysis system,causes the dialysis system to perform operations comprising: raising analarm upon determining that each indicator in the data structureindicates that fluid was absent from the portion of the medical fluidtube.
 4. The system of claim 1, wherein the first period is 5milliseconds and the second period is 995 milliseconds.
 5. The system ofclaim 1, wherein the medical fluid tube has an outer diameter of lessthan 0.128 inch.
 6. The system of claim 1, wherein the medical fluidtube has an inner diameter of less than 0.031 inch.
 7. The system ofclaim 1, wherein the signal is a measure of voltage.
 8. The system ofclaim 7, wherein the threshold value is a first value if fluid wasdetermined to be present during the previous activation of theultrasonic transmitter; the threshold is a second value if the fluid waspreviously determined to be absent during the previous activation of theultrasonic transmitter; and the first value is greater than the secondvalue.
 9. A computer-implemented method comprising: on a control unit ofa dialysis machine: controlling, on a processor of the control unit,repetitive activation of an ultrasonic transmitter, wherein controllingrepetitive activation of the ultrasonic transmitter comprises, for eachrepetition: activating the ultrasonic transmitter for a first period of2 to 15 milliseconds; and deactivating the ultrasonic transmitter for asecond period of 998 to 985 milliseconds; receiving, by the processor ofthe control unit, a signal from an ultrasonic receiver during anactivation of the ultrasonic transmitter; and determining, by theprocessor of the control unit, that fluid is absent or present in aportion of a medical fluid tube of a drug delivery device based on acomparison between the signal and a threshold value.
 10. The method ofclaim 9 further comprising: storing an indicator of the absence orpresence of fluid in a data structure, the data structure storing aplurality of indicators determined during previous activations of theultrasonic transmitter.
 11. The method of claim 10, further comprising:raising an alert upon determining that each indicator in the datastructure indicates that fluid was absent from the portion of themedical fluid tube.
 12. The method of claim 9, wherein the first periodis 5 milliseconds and the second period is 995 milliseconds.
 13. Themethod of claim 9, wherein the medical fluid tube has an outer diameterof less than 0.128 inch.
 14. The method of claim 9, wherein the medicalfluid tube has an inner diameter of less than 0.031 inch.
 15. The methodof claim 9, wherein the signal is a measure of voltage.
 16. The methodof claim 15, wherein the threshold value is a first value if fluid wasdetermined to be present during the previous activation of theultrasonic transmitter; the threshold is a second value if the fluid waspreviously determined to be absent during the previous activation of theultrasonic transmitter; and the first value is greater than the secondvalue.
 17. A dialysis system comprising: a dialysis machine; a controlunit; an ultrasonic transmitter; an ultrasonic receiver; and a computerstorage medium encoded with computer program instructions that whenexecuted by the dialysis system, causes the dialysis system to performoperations comprising: controlling repetitive activation of theultrasonic transmitter, wherein controlling repetitive activation of theultrasonic transmitter comprises, for each repetition: activating theultrasonic transmitter for a first period of 2 to 15 milliseconds; anddeactivating the ultrasonic transmitter for a second period of 998 to985 milliseconds; receiving a signal from the ultrasonic receiver duringan activation of the ultrasonic transmitter; and determining that fluidis absent or present in a portion of a medical fluid tube based on acomparison between the signal and a threshold value.
 18. The system ofclaim 17, wherein the computer storage medium is further encoded withcomputer program instructions that when executed by the dialysis system,causes the dialysis system to perform operations comprising: storing anindicator of the absence or presence of fluid in a data structure, thedata structure storing a plurality of indicators determined duringprevious activations of the ultrasonic transmitter.
 19. The system ofclaim 18, wherein the computer storage medium is further encoded withcomputer program instructions that when executed by the dialysis system,causes the dialysis system to perform operations comprising: raising analarm upon determining that each indicator in the data structureindicates that fluid was absent from the portion of the medical fluidtube.
 20. The system of claim 17, wherein the first period is 5milliseconds and the second period is 995 milliseconds.
 21. The systemof claim 17, wherein the signal is a measure of voltage.
 22. The systemof claim 21, wherein the threshold value is a first value if fluid wasdetermined to be present during the previous activation of theultrasonic transmitter; the threshold is a second value if the fluid waspreviously determined to be absent during the previous activation of theultrasonic transmitter; and the first value is greater than the secondvalue.